Cascading effects of contemporaneous defaunation on tropical forest communities

Background

Defaunation, caused by hunting and habitat fragmentation, is a major threat to biodiversity in tropical forests. It disproportionately affects large-bodied vertebrates, which play key roles as seed dispersers, seed predators, and herbivores. The loss of these animals can have cascading effects on plant populations, altering species composition, seed dispersal, and plant recruitment. This study reviews empirical evidence from 42 studies to understand how defaunation influences plant-animal interactions, plant demography, and overall community diversity.

Goals and Methods

The study aims to assess the indirect effects of defaunation on tropical forest plant communities by synthesizing data from multiple studies. The researchers analyzed how defaunation influences key ecological processes such as seed dispersal, seed predation, herbivory, and trampling. By examining these interactions, they sought to determine the broader consequences of wildlife loss on plant recruitment, seedling survival, and overall species diversity. To ensure consistency across different study sites, they standardized response variables, allowing for meaningful comparisons of defaunation effects across varying levels of species loss

Conclusion

Defaunation leads to a significant reduction in seed dispersal, especially for large-seeded species dependent on large vertebrates. While seed predation and herbivory decrease in some cases, they increase in others due to shifts in animal populations. The net effect is a decline in plant species richness, increased dominance of certain species, and shifts in functional traits of plant communities. The study highlights that defaunation is not just a biodiversity crisis but also a driver of ecological change that alters forest dynamics.